Polymorphisms of Mannose-binding Lectin and Toll-like Receptors 2, 3, 4, 7 and 8 and the Risk of Respiratory Infections and Acute Otitis Media in Children

Genetic polymorphisms of TLR1, TLR2, TLR3 and TLR4 in patients with recurrent or severe infections

Toll-like receptors (TLRs) play an important role in innate immunity. Previous studies have shown that single nucleotide polymorphisms (SNPs) in the genes coding for these innate immune molecules can affect susceptibility to and the outcome of certain diseases. The aim of the present study was to examine the clinical relevance of well-studied TLR1-4 SNPs in individuals who are prone to infections. Four functional SNPs, TLR1 rs5743618 (1805C > A, Ser602Ile), TLR2 rs5743708 (2258G > A, Arg753Gln), TLR3 rs3775291 (1234C > T, Leu412Phe) and TLR4 rs4986790 (896A > G, Asp299Gly), were analysed in 155 patients with recurrent respiratory infections (n = 84), severe infections (n = 15) or common variable immunodeficiency (n = 56), and in 262 healthy controls, using the High Resolution Melting Analysis method. Polymorphisms of TLR2 rs5743708 (odds ratio [OR] 3.16; 95% confidence interval [CI] 1.45-6.83, p = .004, ap = .016) and TLR4 rs4986790 (OR 1.8; 95% CI 1.05-3.12, p = .028, ap = .112) were more frequent in patients with recurrent or severe infections than in controls. Interestingly, seven patients were found to carry both variant genotypes of TLR2 and TLR4, whereas none of the control group carried such genotypes (p  ≤ .0001). Moreover, TLR2 polymorphism was associated with increased risk for acute otitis media episodes (OR, 3.02; 95% CI 1.41-6.47; p = .012). This study indicates that children and adults who are more prone to recurrent or severe respiratory infections carry one or both variant types of TLR2 and TLR4 more often than control subjects. Genetic variations of TLRs help explain why some children are more susceptible to respiratory infections.

Mannose-binding lectin gene sequence data in Kelantan population

The human mannose-binding lectin (MBL) gene encodes a polymorphic protein that plays a crucial role in the innate immune response. Human MBL deficiency is associated with immunodeficiencies, and its variants have been linked to autoimmune and infectious diseases. Despite this significance, gene studies concerning MBL sequencing are uncommon in Malaysia. Therefore, we aimed to preliminary described the human MBL sequencing dataset based on the Kelantan population. Blood samples were collected from 30 unrelated individuals and underwent DNA extraction, genotyping, and sequencing. The sequencing data generated 886 bp, which were deposited in GenBank (ON619541-ON619546). Allelic variants were identified and translated into six MBL haplotypes: HYPA, HYPB, LYPB, LXPB, HXPA, and LXPA. An evolutionary tree was constructed using the haplotype sequences. These findings contribute to the expansion of MBL information within the country, providing a valuable baseline for future research exploring the association between the gene and targeted diseases.

Ficolin-3 and MASP-2 gene variants in Siberian arctic populations: Summarized evidence of selective pressure for the high frequency of lectin complement pathway deficiency

Herewith, we provide novel original data about the prevalence of FCN3 rs532781899 and MASP2 rs72550870 variants among the newborns of aboriginal Siberian Arctic populations (Nenets and Dolgan-Nganasans) and Russians of East Siberia. This novel data has been analysed along with the genetic data about other proteins of the lectin pathway of the complement system (mannose-binding lectin and ficolin-2) obtained earlier. A total of 926 specimens of dried blood spots of the newborns were genotyped. The newborns represented four populations: Nenets, Dolgan-Nganasans, Mixed aboriginal population, and Russians (Caucasians) to study the prevalence of single nucleotide polymorphisms of FCN3 rs532781899 and MASP2 rs72550870. The prevalence of the deletion allele of the rs532781899 variant in the FCN3 gene associated with the decreased production of ficolin-3 was found to be increased in Russians compared to the Nenets aboriginal populations (P = .002). The prevalence of the rs72550870*G allele in the MASP2 gene associated with low serum protease activity was found to be increased in Russians compared with Nenets and Dolgan-Nganasans (P < .001 and P = .03, respectively). The results of the current study and our previous findings corroborate with a hypothesis that human evolution has been directed toward the accumulation of genotypes associated with low activity of the lectin complement activation pathway.

Mannose-binding lectin genotype is associated with respiratory disease in young children: A multicenter cohort study

BACKGROUND

Mannose-binding lectin (MBL) is an important component of the innate immune system. Polymorphisms in the MBL2 gene and promoter region are directly associated with MBL-deficiency. We sought to determine the association between MBL genotype on the frequency of common childhood respiratory infections, respiratory symptoms, and atopic outcomes in early childhood.

METHODS

MBL2 gene variants were analyzed in newborns recruited to the GO-CHILD multicenter prospective cohort study. Follow-up for respiratory infection and atopy diagnoses and symptoms, healthcare utilization, and medication prescription were conducted by postal questionnaires at 12 and 24 months.

RESULTS

Genotyping and follow-up were completed in 1004 children. Genotypes associated with MBL-deficiency were associated with an increased risk of bronchiolitis (relative risk [RR] 1.95, 95% confidence interval [CI] 1.33-2.85) and pneumonia (RR 2.46, 95% CI 1.16-5.22). MBL-deficient genotypes were associated with an increased risk of wheeze with shortness of breath episodes (RR 1.22, 95% CI 1.04-1.43), emergency department attendance (RR 1.90 95% CI 1.13-3.19), and hospital admission (RR 2.01, 95% CI 1.04-3.89) for wheeze. MBL-deficient genotypes were associated with a reduced risk of developing atopic dermatitis (RR 0.72, 95% CI 0.53-0.98).

CONCLUSION

The positive association between MBL-deficient genotypes and bronchiolitis and pneumonia, as well as a severe wheeze phenotype in some young children, supports the hypothesis that MBL is an important component of innate immunity in the vulnerable period before the maturation of the adaptive immune system. Identification of disease-modifying genotypes may help target preventative strategies in high-risk infants.

Surfactant proteins and innate immunity of otitis media

Otitis media (OM) is the most common disease among young children and one of the most frequent reasons to visit the pediatrician. Development of OM requires nasopharyngeal colonization by a pathogen which must gain access to the tympanic cavity through the eustachian tube (ET) along with being able to overcome the defense mechanisms of the immune system and middle ear mucosa. OM can be caused by viral or bacterial infection. The three main bacterial pathogens are Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), and Moraxella catarrhalis. Innate immunity is important in OM resolution as the disease occurs in very young children before the development of specific immunity. Elements of innate immunity include natural barriers and pattern recognition receptors such as Toll like receptors (TLRs), and Nod like receptors (NLRs). Surfactant proteins A (SP-A) and D (SP-D) act as pattern recognition receptors and are found in the lung and many other tissues including the ET and the middle ear where they probably function in host defense. Surfactant has a potential for use in the treatment of OM due to surface tension lowering function in the ET, and the possible immune functions of SP-D and SP-A in the middle ear and ET.

The ECRG4 cleavage product augurin binds the endotoxin receptor and influences the innate immune response during otitis media

Otitis media (OM), the most common disease of childhood, is typically characterized by bacterial infection of the middle ear (ME). Prominent features of OM include hyperplasia of the ME mucosa, which transforms from a monolayer of simple squamous epithelium with minimal stroma into a full-thickness respiratory epithelium in 2-3 days after infection. Analysis of the murine ME transcriptome during OM showed down-regulation of the tumor suppressor gene Ecrg4 that was temporally related to mucosal hyperplasia and identified stromal cells as the primary ECRG4 source. The reduction in Ecrg4 gene expression coincided with the cleavage of ECRG4 protein to release an extracellular fragment, augurin. The duration of mucosal hyperplasia during OM was greater in Ecrg4 ^-/- mice, the number of infiltrating macrophages was enhanced, and ME infection cleared more rapidly. ECRG4-null macrophages showed increased bacterial phagocytosis. Co-immunoprecipitation identified an association of augurin with TLR4, CD14 and MD2, the components of the lipopolysaccharide (LPS) receptor. The results suggest that full-length ECRG4 is a sentinel molecule that potentially inhibits growth of the ME stroma. Processing of ECRG4 protein during inflammation, coupled with a decline in Ecrg4 gene expression, also influences the behavior of cells that do not express the gene, limiting the production of growth factors by epithelial and endothelial cells, as well as the activity of macrophages.

Immunomodulation as a Protective Strategy in Chronic Otitis Media

Introduction

Major features of the pathogenesis in otitis media, the most common disease in childhood, include hyperplasia of the middle ear mucosa and infiltration by leukocytes, both of which typically resolve upon bacterial clearance via apoptosis. Activation of innate immune receptors during the inflammatory process leads to the activation of intracellular transcription factors (such as NF-κB, AP-1), which regulate both the inflammatory response and tissue growth. We investigated these leading signaling pathways in otitis media using mouse models, human samples, and human middle ear epithelial cell (HMEEC) lines for therapeutic immunomodulation.

Methods

A stable otitis media model in wild-type mice and immunodeficient KO-mice, as well as human tissue samples from chronic otitis media, skin from the external auditory canal and middle ear mucosa removed from patients undergoing ear surgery, were studied. Gene and protein expression of innate immune signaling molecules were evaluated using microarray, qPCR and IHC. In situ apoptosis detection determined the apoptotic rate. The influence of bacterial infection on immunomodulating molecules (TNFα, MDP, Tri-DAP, SB203580, Cycloheximide) in HMEEC was evaluated. HMEEC cells were examined after bacterial stimulation/inhibition for gene expression and cellular growth.

Results

Persistent mucosal hyperplasia of the middle ear mucosa in chronic otitis media resulted from gene and protein expression of inflammatory and apoptotic genes, including NODs, TNFα, Casp3 and cleaved Casp3. In clinical chronic middle ear samples, these molecules were modulated after a specific stimulation. They also induced a hyposensitive response after bacterial/NOD-/TLR-pathway double stimulation of HMEEC cells in vitro. Hence, they might be suitable targets for immunological therapeutic approaches.

Conclusion

Uncontrolled middle ear mucosal hyperplasia is triggered by TLRs/NLRs immunoreceptor activation of downstream inflammatory and apoptotic molecules.

Innate Immunity in the Middle Ear Mucosa

Otitis media (OM) encompasses a spectrum of clinical presentations ranging from the readily identifiable Acute OM (AOM), which is characterised by otalgia and fever, to chronic otitis media with effusion (COME) where impaired hearing due to middle ear effusion may be the only clinical symptom. Chronic suppurative OM (CSOM) presents as a more severe form of OM, involving perforation of the tympanic membrane. The pathogenesis of OM in these varied clinical presentations is unclear but activation of the innate inflammatory responses to viral and/or bacterial infection of the upper respiratory tract performs an integral role. This localised inflammatory response can persist even after pathogens are cleared from the middle ear, eustachian tubes and, in the case of respiratory viruses, even the nasal compartment. Children prone to OM may experience an over exuberant inflammatory response that underlies the development of chronic forms of OM and their sequelae, including hearing impairment. Treatments for chronic effusive forms of OM are limited, with current therapeutic guidelines recommending a "watch and wait" strategy rather than active treatment with antibiotics, corticosteroids or other anti-inflammatory drugs. Overall, there is a clear need for more targeted and effective treatments that either prevent or reduce the hyper-inflammatory response associated with chronic forms of OM. Improved treatment options rely upon an in-depth understanding of OM pathogenesis, particularly the role of the host innate immune response during acute OM. In this paper, we review the current literature regarding the innate immune response within the middle ear to bacterial and viral otopathogens alone, and as co-infections. This is an important consideration, as the role of respiratory viruses as primary pathogens in OM is not yet fully understood. Furthermore, increased reporting from PCR-based diagnostics, indicates that viral/bacterial co-infections in the middle ear are more common than bacterial infections alone. Increasingly, the mechanisms by which viral/bacterial co-infections may drive or maintain complex innate immune responses and inflammation during OM as a chronic response require investigation. Improved understanding of the pathogenesis of chronic OM, including host innate immune response within the middle ear is vital for development of improved diagnostic and treatment options for our children.

Toll-Like Receptors: Expression and Roles in Otitis Media

Otitis media is mainly caused by upper respiratory tract infection and eustachian tube dysfunction. If external upper respiratory tract infection is not detected early in the middle ear, or an appropriate immune response does not occur, otitis media can become a chronic state or complications may occur. Therefore, given the important role of Toll-like receptors (TLRs) in the early response to external antigens, we surveyed the role of TLRs in otitis media. To summarize the role of TLR in otitis media, we reviewed articles on the expression of TLRs in acute otitis media (AOM), otitis media with effusion (OME), chronic otitis media (COM) with cholesteatoma, and COM without cholesteatoma. Many studies showed that TLRs 1–10 are expressed in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. TLR expression in the normal middle ear mucosa is absent or weak, but is increased in inflammatory fluid of AOM, effusion of OME, and granulation tissue and cholesteatoma of COM. In addition, TLRs show increased or decreased expression depending on the presence or absence of bacteria, recurrence of disease, tissue type, and repeated surgery. In conclusion, expression of TLRs is associated with otitis media. Inappropriate TLR expression, or delayed or absent induction, are associated with the occurrence, recurrence, chronicization, and complications of otitis media. Therefore, TLRs are very important in otitis media and closely related to its etiology.

Assessing the impact of acute respiratory illnesses on the risk of subsequent respiratory illness

BACKGROUND

Whether acute respiratory illnesses (ARIs), often associated with virus detection, are associated with lower risk for subsequent ARI remains unclear. We assessed the association between symptomatic ARI and subsequent ARI in young children.

METHODS

In a prospective cohort of Peruvian children <3 years, we examined the impact of index ARI on subsequent ARI risk. Index ARI were matched with ≤3 asymptomatic observations and followed over 28 days. We compared risk of subsequent ARI between groups using conditional logistic regression adjusting for several covariates, accounting for repeat observations from individual children.

RESULTS

Among 983 index ARI, 339 (34%) had an ARI event during follow-up, compared with 876/2826 (31%) matched asymptomatic observations. We found no significant association of index ARI and subsequent ARI risk during follow-up overall (aOR 1.10, 95% CI 0.98, 1.23) or when limited to index ARI with respiratory viruses detected (aOR 1.03, 95% CI 0.86, 1.24). Similarly, when the outcome was limited to ARI in which viruses were detected, no significant association was seen (aOR 1.05, 95% CI 0.87, 1.27).

DISCUSSION

ARIs were not associated with short-term protection against subsequent ARI in these children. Additional longitudinal studies are needed to understand drivers of recurrent ARI in young children.

Interactions of genetic variants and prenatal stress in relation to the risk for recurrent respiratory infections in children

Genetic variants may predispose children to recurrent respiratory infections (RRIs) but studies on genotype-environment interaction are rare. We hypothesized that the risk for RRIs is elevated in children with innate immune gene variants, and that prenatal exposure to maternal psychological distress further increases the risk. In a birth cohort, children with RRIs (n = 96) were identified by the age of 24 months and compared with the remaining cohort children (n = 894). The risk for RRIs in children with preselected genetic variants and the interaction between maternal distress during pregnancy and child genotype were assessed with logistic regression. The IL6 minor allele G was associated with elevated risk for RRIs (OR 1.55; 95% CI 1.14-2.12). Overall, there was no interaction between maternal psychological distress and child genotype. Exploratory analyses showed that, the association between the variant type of IL6 and the risk for RRIs was dependent on prenatal exposure to maternal psychological distress in males (OR 1.96; 95% CI 1.04-3.67). Our study didn't find genotype-environment interaction between prenatal maternal distress and child genotype. Exploratory analyses suggest sex differences in gene-environment interaction related to susceptibility to RRIs.

A SNaPshot Assay for Determination of the Mannose-Binding Lectin Gene Variants and an Algorithm for Calculation of Haplogenotype Combinations

Mannose-binding lectin (MBL) deficiency caused by the variability in the MBL2 gene is responsible for the susceptibility to and severity of various infectious and autoimmune diseases. A combination of six single nucleotide polymorphisms (SNPs) has a major impact on MBL levels in circulation. The aim of this study is to design and validate a sensitive and economical method for determining MBL2 haplogenotypes. The SNaPshot assay is designed and optimized to genotype six SNPs (rs1800451, rs1800450, rs5030737, rs7095891, rs7096206, rs11003125) and is validated by comparing results with Sanger sequencing. Additionally, an algorithm for online calculation of haplogenotype combinations from the determined genotypes is developed. Three hundred and twenty-eight DNA samples from healthy individuals from the Czech population are genotyped. Minor allele frequencies (MAFs) in the Czech population are in accordance with those present in the European population. The SNaPshot assay for MBL2 genotyping is a high-throughput, cost-effective technique that can be used in further genetic-association studies or in clinical practice. Moreover, a freely available online application for the calculation of haplogenotypes from SNPs is developed within the scope of this project.

Associations Between IFI44L Gene Variants and Rates of Respiratory Tract Infections During Early Childhood

Background

Genetic heterogeneity in type I interferon (IFN)–related gene IFI44L may account for variable susceptibility to respiratory tract infections (RTIs) in children.

Methods

In 2 prospective, population-based birth cohorts, the STEPS Study and the FinnBrain Birth Cohort Study, IFI44L genotypes for rs273259 and rs1333969 were determined in relation to the development of RTIs until 1 or 2 years of age, respectively. At age 3 months, whole-blood transcriptional profiles were analyzed and nasal samples were tested for respiratory viruses in a subset of children.

Results

In the STEPS Study (n = 1135), IFI44L minor/minor gene variants were associated with lower rates of acute otitis media episodes (adjusted incidence rate ratio, 0.77 [95% confidence interval, .61–.96] for rs273259 and 0.74 [.55–.99] for rs1333969) and courses of antibiotics for RTIs (0.76 [.62–.95] and 0.73 [.56–.97], respectively. In the FinnBrain cohort (n = 971), IFI44L variants were associated with lower rates of RTIs and courses of antibiotics for RTIs. In respiratory virus–positive 3-month-old children, IFI44L gene variants were associated with decreased expression levels of IFI44L and several other IFN-related genes.

Conclusions

Variant forms of IFI44L gene were protective against early-childhood RTIs or acute otitis media, and they attenuated IFN pathway activation by respiratory viruses.

Panel 7 - Pathogenesis of otitis media - a review of the literature between 2015 and 2019

OBJECTIVE

To perform a comprehensive review of the literature from July 2015 to June 2019 on the pathogenesis of otitis media. Bacteria, viruses and the role of the microbiome as well as the host response are discussed. Directions for future research are also suggested.

DATA SOURCES

PubMed database of the National Library of Medicine.

REVIEW METHODS

PubMed was searched for any papers pertaining to OM pathogenesis between July 2015 and June 2019. If in English, abstracts were assessed individually for their relevance and included in the report. Members of the panel drafted the report based on these searches and on new data presented at the 20th International Symposium on Recent Advances in Otitis Media.

CONCLUSIONS

The main themes that arose in OM pathogenesis were around the need for symptomatic viral infections to develop disease. Different populations potentially having different mechanisms of pathogenesis. Novel bacterial otopathogens are emerging and need to be monitored. Animal models need to continue to be developed and used to understand disease pathogenesis.

IMPLICATIONS FOR PRACTICE

The findings in the pathogenesis panel have several implications for both research and clinical practice. The most urgent areas appear to be to continue monitoring the emergence of novel otopathogens, and the need to develop prevention and preventative therapies that do not rely on antibiotics and protect against the development of the initial OM episode.

Panel 2- recent advance in otitis media bioinformatics

OBJECTIVES

To update the medical literature on recent large-scale studies employing bioinformatics data analysis tools in otitis media (OM) disease models with a principal focus on developments in the past 5 years.

DATA SOURCES

Pubmed indexed peer-reviewed articles.

REVIEW METHODS

Comprehensive review of the literature using the following search terms: 'genomics, inflammasome, microRNA, proteomics, transcriptome, bioinformatics' with the term 'otitis media', and 'middle ear'. Included articles published in the English language from January 1, 2015-April 1, 2019.

IMPLICATIONS FOR PRACTICE

Large scale bioinformatics tools over the past five years lend credence to the paradigm of innate immune response playing a critical role in host defense against bacteria contributing to Otitis Media (OM) progression from acute to chronic. In total, genomic, miRNAomic, and proteomic analyses all point to the need for a tightly regulated innate immune and inflammatory response in the middle ear. Currently, there is an urgent need for developing novel therapeutic strategies to control immunopathology and tissue damage, improve hearing and enhance host defense for both acute and chronic OM based on full understanding of the basic molecular pathogenesis of OM.

Panel 8: Vaccines and immunology

OBJECTIVE

To review and highlight significant advances made towards vaccine development and understanding of the immunology of otitis media (OM) since the 19th International Symposium on Recent Advances in Otitis Media (ISOM) in 2015, as well as identify future research directions and knowledge gaps.

DATA SOURCES

PubMed database, National Library of Medicine.

REVIEW METHODS

Key topics were assigned to each panel member for detailed review. Draft reviews were collated, circulated, and thoroughly discussed when the panel met at the 20th ISOM in June 2019. The final manuscript was prepared with input from all panel members.

CONCLUSIONS

Since 2015 there have been a number of studies assessing the impact of licensed pneumococcal vaccines on OM. While these studies have confirmed that these vaccines are effective in preventing carriage and/or disease caused by vaccine serotypes, OM caused by non-vaccine serotype pneumococci and other otopathogens remains a significant health care burden globally. Development of multi-species vaccines is challenging but essential to reducing the global burden of OM. Influenza vaccination has been shown to prevent acute OM, and with novel vaccines against nontypeable Haemophilus influenzae (NTHi), Moraxella catarrhalis and Respiratory Syncytial Virus (RSV) in clinical trials, the potential to significantly prevent OM is within reach. Research into alternative vaccine delivery strategies has demonstrated the power of maternal and mucosal vaccination for OM prevention. Future OM vaccine trials must include molecular diagnostics of middle ear effusion, for detection of viruses and bacteria that are persisting in biofilms and to enable accurate assessment of vaccine impact on OM etiology. Understanding population differences in natural and vaccine-induced immune responses to otopathogens is also important for development of the most effective OM vaccines. Improved understanding of the interaction between otopathogens will also advance development of effective therapies and encourage the assessment of the indirect benefits of vaccination.

IMPLICATIONS FOR PRACTICE

While NTHi and M. catarrhalis are the predominant otopathogens, funding opportunities to drive vaccine development for these species are limited due to a focus on prevention of childhood mortality rather than morbidity. Delivery of a comprehensive report on the high financial and social costs of OM, including the potential for OM vaccines to reduce antibiotic use and subsequent development of antimicrobial resistance (AMR), would likely assist in engaging stakeholders to recognize the value of prevention of OM and increase support for efforts on OM vaccine development. Vaccine trials with OM prevention as a clinical end-point are challenging, however a focus on developing assays that measure functional correlates of protection would facilitate OM vaccine development.

Current Understanding of Host Genetics of Otitis Media

The pathogenesis of otitis media (OM), an inflammatory disease of the middle ear (ME), involves interplay between many different factors, including the pathogenicity of infectious pathogens, host immunological status, environmental factors, and genetic predisposition, which is known to be a key determinant of OM susceptibility. Animal models and human genetics studies have identified many genes and gene variants associated with OM susceptibility: genes that encode components of multiple signaling pathways involved in host immunity and inflammatory responses of the ME mucosa; genes involved in cellular function, such as mucociliary transport, mucin production, and mucous cell metaplasia; and genes that are essential for Eustachian tube (ET) development, ME cavitation, and homeostasis. Since our last review, several new mouse models with mutations in genes such as CCL3, IL-17A, and Nisch have been reported. Moreover, genetic variants and polymorphisms in several genes, including FNDC1, FUT2, A2ML1, TGIF1, CD44, and IL1-RA variable number tandem repeat (VNTR) allele 2, have been identified as being significantly associated with OM. In this review, we focus on the current understanding of the role of host genetics in OM, including recent discoveries and future research prospects. Further studies on the genes identified thus far and the discovery of new genes using advanced technologies such as gene editing, next generation sequencing, and genome-wide association studies, will advance our understanding of the molecular mechanism underlying the pathogenesis of OM and provide new avenues for early screening and developing effective preventative and therapeutic strategies to treat OM.

Infant Immune Response to Respiratory Viral Infections

Of all respiratory viruses that affect infants, respiratory syncytial virus (RSV) and rhinovirus (RV) represent the leading pathogens causing acute disease (bronchiolitis) and are associated with the development of recurrent wheezing and asthma. The immune system in infants is still developing, and several factors contribute to their increased susceptibility to viral infections. These factors include differences in pathogen detection, weaker interferon responses, lack of immunologic memory toward the invading pathogen, and T-cell responses that are balanced to promote tolerance and restrain inflammation. These aspects are reviewed here with a focus on RSV and RV infections.

The Interaction of Human Pathogenic Fungi With C-Type Lectin Receptors

Fungi, usually present as commensals, are a major cause of opportunistic infections in immunocompromised patients. Such infections, if not diagnosed or treated properly, can prove fatal. However, in most cases healthy individuals are able to avert the fungal attacks by mounting proper antifungal immune responses. Among the pattern recognition receptors (PRRs), C-type lectin receptors (CLRs) are the major players in antifungal immunity. CLRs can recognize carbohydrate ligands, such as β-glucans and mannans, which are mainly found on fungal cell surfaces. They induce proinflammatory immune reactions, including phagocytosis, oxidative burst, cytokine, and chemokine production from innate effector cells, as well as activation of adaptive immunity via Th17 responses. CLRs such as Dectin-1, Dectin-2, Mincle, mannose receptor (MR), and DC-SIGN can recognize many disease-causing fungi and also collaborate with each other as well as other PRRs in mounting a fungi-specific immune response. Mutations in these receptors affect the host response and have been linked to a higher risk in contracting fungal infections. This review focuses on how CLRs on various immune cells orchestrate the antifungal response and on the contribution of single nucleotide polymorphisms in these receptors toward the risk of developing such infections.

Respiratory syncytial virus in Brazilian infants - Ten years, two cohorts

•

There was 33.1% and 70.3% of RSV patients, respectively, in 2004 and 2014.

•

The month of incidence was different between the cohorts.

•

First cohort: higher age at attendance and number of co-morbidities.

•

Second cohort: lower birth weight and gestational age.

Background

Each year, a considerable amount of children will experience at least one episode of acute viral bronchiolitis (AVB) during their first year of life. About 10% of them will be hospitalized, with significant physical and economic burdens.

Objectives

To compare two cohorts of infants with AVB, from same region, in a ten-year interval, regarding epidemiologic factors and viral etiology.

Study design

Cohorts: 142 (2004) and 172 (2014) infants at ages zero to 12 months; clinical diagnosis of AVB; medical care in hospital and genetic screening of nasopharyngeal secretion for respiratory viruses.

Results

The comparative analysis showed a difference in the percentage of respiratory syncytial virus (RSV) positive patients [2004 (33.1%); 2014 (70.3%)] (p < 0.01). No differences were noted regarding gender, breastfeeding, tobacco exposure, crowding and maternal education. There was a difference as to the month of incidence (seasonality) of AVB (higher in April 2014). There was a higher age at attendance in the first cohort, and lower birth weight and gestational age ratios in the second cohort (p < 0.05). There were no differences in hospitalization time, need of mechanical ventilation and number of deaths, however a difference regarding co-morbidities was noted (higher in 2004) (p < 0.001).

Conclusion

None of the analyzed variables had an impact on severity features. Virology and immunology must be considered in this kind of situation, by studying genetic variants and the maturation of the immune system in AVB by RSV or other viruses.